drm/i915: Make wait-for-pending-flips more defensive

Be sure to always flush a stuck pageflip even if we couldn't possibly
expect one to be there.

References: https://bugs.freedesktop.org/show_bug.cgi?id=82612
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 5 insertions, 7 deletions

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index dec7287ad0c2..921594f64158 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3363,18 +3363,16 @@ void intel_crtc_wait_for_pending_flips(struct drm_crtc *crtc)
         struct drm_device *dev = crtc->dev;
         struct drm_i915_private *dev_priv = dev->dev_private;
 
-        if (crtc->primary->fb == NULL)
-                return;
-
         WARN_ON(waitqueue_active(&dev_priv->pending_flip_queue));
-
         WARN_ON(wait_event_timeout(dev_priv->pending_flip_queue,
                                    !intel_crtc_has_pending_flip(crtc),
                                    60*HZ) == 0);
 
-        mutex_lock(&dev->struct_mutex);
-        intel_finish_fb(crtc->primary->fb);
-        mutex_unlock(&dev->struct_mutex);
+        if (crtc->primary->fb) {
+                mutex_lock(&dev->struct_mutex);
+                intel_finish_fb(crtc->primary->fb);
+                mutex_unlock(&dev->struct_mutex);
+        }
 }
 
 /* Program iCLKIP clock to the desired frequency */